This invention concerns a filler primer for repair car-refinishing, and specifically a primer containing no organic solvents and featuring improved vertical application characteristics and a particularly rapid drying speed.
The purpose of filler primers in repair car-refinishing is to provide a protective coat for the body-work and at the same time to create a suitable undercoat for the enamel.
The composition of these primers is usually rather complex, involving pigments and extenders, binders, solvents and additives.
A primer must incorporate certain definite properties, the most important of which are a good vertical coatability and a relatively fast hardening time.
The binder plays a fundamental role in determining the above properties.
Currently-used primers contain polyacrylate resins as a binder. To create a proper receipe these resins must be dissolved in organic solvents, such as glycols, diacetone alcohol, butanol, or similar substances. The solvent reaches concentrations of between 8-15% in the final composition. Such high solvent concentrations create a serious environmental problem from two points of view, i.e. safety, and the health of the workers exposed to these solvents, not only at the level of preparation but also at the level of the final utilisation.
To this problem can be added further difficulties encountered in the utilisation of known primers, which do not exceed a verticality value of 20 .mu.m at each coat, have unsatisfactory filling power and coverage, are liable to drip during the application, and need at least four hours to dry.
For the above-mentioned reasons, therefore, a primer containing no solvents is highly desirable. There is also a real need for a primer with improved application properties.